Slack motion take-up device



Filed Dec. 20, 1933 INVENTORS I WILLIAM NAPOLEON FREDERICK ALLARD JOHN HoYEM BY A? TTORNEYS Patented Oct. 30, 1934 SLACK. MOTION TAKE-U1. DEVICE.

William Napoleon Frederick. Allard, New Wests minstei', British Columbia, andf Jolin Hoyema Fraser Mills, British Columbia, Ganadw;

ApplicationD'ecember 20,1933; SerialNo. 703,240

' 3 (3laims. (Cl. Lilli-121) Qur invention relates; to improvementsrin slack motion take. up? devices-which are particularly adapted fonusednisawmill carriages 'or carriages for supporting; work to; be mechanically acted 'Ilhegobject-ofitheinvention-isto provide: means wherebyyaworkasupport will-be soheld-that movement thereof will be simultaneous with the suppqrtzlmojving.meansyor.thatlslack motionbetween m the moving means and the support, shall be en tirely eliminated. A further object is to provide a rearward tension upon the support which will progressively increase as said support is moved forwardly.

In a saw mill carriage a log is dogged to the several knees before being sawn longitudinally and frequently after a slab has been taken 01f. and the log turned the dogs on being forced into the log will be drawn slightly forward in advance of the feed screw or rack, with the consequence that when the set works are set in motion one or more knees will, through previous forward movement,

be urged forward by the log and move in advance of the feed screw or rack and crooked lumher will result. To eliminate this defect it is necessary that the inherent spring of a log should be overcome, and that the log be dogged in absolute contact with a knee and the knee be so held as to move simultaneously and only with the g movement of the set works and entirely in unison with the remaining knees on the carriage,

irrespective of the wear of the screw or other feed works by which the knee is advanced.

The invention consists of a spring tension interposed between a knee and its feed mechanism for the purpose of preventing slack motion, particularly when the feed mechanism is operating to move the knee in a predetermined direction, as

will be more fully described in the following 5740 specification and shown in the accompanying drawing, in which:

' Fig. 1 is a view showing the invention applied to a head block of a saw mill carriage equipped with a screw feed works.

. Fig. 2 is a similar view showing a rack and pinion feed works.

Fig. 3 is a similar view showing a modification A of the invention.

In the drawing like characters of reference ini ifip dicate corresponding parts in each figure.

While the invention is applicable to many machines, it is here shown, for the purpose of description, as applied to a saw mill carriage.

The numeral 1 indicates generally a head block of a saw mill carriage upon which a knee 2 is slidablyq mountemthe head block. isrfittedlwitha bearing 3-in-which-a1feed screw 4- is journalled. The feed screw ids-fitted at itsrear endwithra mitre gear 5-whichis driven-froma similar, gear 6 slidably fittedupon alay shaft 7 extending be yond thezends of. thehead blocks. Fromkthe unders-ideof the knee 2 abearing collar'8textends, against. which anon-rotating nut 9 engaging the screw-4; thrusts. Suitably mounted ,uponthe car.- riage adjacent each head block is a winding gear 10 which obviously travels with said head block and consists of a drum 11 fitted with a sprocket 12 driven by a chain 13 from a sprocket 14 which is coupled to a further sprocket 15 which is driven by a chain 16 from a slidably mounted sprocket 7,0 17 upon the lay shaft 7. The drum is so geared as to have a peripheral speed slightly slower than the knee 2 with which it is connected. This drum is fitted with a cable 18 having at its free end a turnbuckle 19 for the purpose of adjustment. 7,5 The turnbuckle is anchored by a fork 20 to a compression spring 21 and the spring in turn is anchored to the knee 2 by a further fork 22 and a. bracket 23. The spring is brought under sufficient tension when the knee is adjacent to the lay .shaft '7, so that when entering the dog 24 into any log to be out, it will draw said log into intimate contact with the knee or any spacer which may be interposed between the log and knee and still maintain the rear face of the thread of the nut 9 in contact with the forward face of the thread of the feed screw 4.

In the modification shown in Figure 2, the knee 2 is fitted on its underside with an inverted rack 25 which is driven from the lay shaft 7 through a train of sprockets and chains 26 and a pinion 27 journalled in suitable bearings mounted upon the head block 1.

In the modification shown in Figure 3, which is applicable to any screw feed, a second nut indicated by the numeral 28 is non-rotatably mounted upon the screw 4 and is provided with an upstanding fork 29 between which and the knee 2 a turnbuckle 19 and a spring 21 are connected. It will be obvious that a tension spring may be substituted in place of the compression spring 21 without departing from the spirit of the invention.

In the devices shown in Figures 1 and 2, each time the knees are moved forwardly toward the log the cable 18 is paid out at a slightly less speed 0 and distance than that of the knee, so that the spring 21 is compressed to a greater extent, thus increasing the effort thrusting the nut 9, as in Figure 1, against the forward side of the threads of the screw 4 and some of the teeth of the rack 25 against the leading side of the teeth of the pinion 2'? as shown in Fig. 2, therefore as the log is reduced in size due to cutting ofi slabs and its tendency to spring or warp is increased, so a greater force is applied through the spring 21 to draw it back to line, hence straight lumber is out.

In the modification shown in Figure 3 the spring tension remains constant except for wear taking place in the thread or the nut, which wear is compensated for by tightening up on the turnbuckle 19 as is resorted to in the devices shown in Figures 1 and 2.

In view of the great wear which both worm and rack and pinion feeds are subjectedto, slack soon develops and by the use of this invention the slack motion between the knee and said feed mechanism is entirely eliminated and accurate work is maintained.

What we claim as our invention is, 1' 1. The combination with a sawmill carriage headblock and a lay shaft, a knee slidable'upon the headblo'ck, a winding gear movable with the headblock and driven-from the lay shaft, a feed screw driven from said lay shaft, a collar depending from the knee surrounding the feed screw, a non-rotating nut upon said feed screw adapted to engage the collar to move the knee in one direc- 'tion, and a cable extending from the winding gear to the knee to move said knee in the opposite "direction.

Bil

"the opposite direction, and spring means interposed between said cable and the knee adapted to keep the collar in firm contact with the nonrotating nut.

The combination with a sawmill carriage headblock and a layshaft, a knee slidable upon the headblock, a winding gear movable with the headblock and driven from the lay shaft, a feed (,screwdriven from said lay shaft, a collar depending from the knee surrounding the feed screw, a non-rotating nut upon said feed screw adapted to engage the collar to move the knee'in one direction, and a cable extending from the winding gear to the knee to move said knee in the opposite direction, said winding gear and feed screw being of such ratio as to provide aslightly slower movement to the cable than to the knee.

WILLIAM NAPOLEON FREDERICK ALLARD. 7,

JOHN HOYEM. 

